Projection system



March 17, 1964 e. MURRAY ETAL 3,125,635

PROJECTION SYSTEM Filed June 5, 1962 37 Screen ./nvem0rs James 6. Murray Freaer/c/r F Halub;

b MTW I The/r Affo ney United States Patent 3,125,635 PRUJECTION SYSTEM James G. Murray and Frederick F. Holub, Scotia, and Matthew .1. mith, chenectady, N.Y., assignors to General Electric Company, a corporation of New York Filed June 5, 1962, Ser. No. 200,075 8 Ciainls. (Cl. 178-7.5)

This invention is concerned with a projection system utilizing a certain deformable medium. More particularly, the invention is concerned with a projection system comprising a container having a conducting interior, a deformable medium in said container that decreases 1n resistivity with decreases in thickness and in the presence of an electrical charge on the surface thereof comprising a composition having the formula where R is a monovalent hydrocarbon radical selected from the class consisting of the methyl radical, aromatic radicals (e.g., phenyl, biphenylyl, terphenylyl, naphthyl, etc. radicals), and a radical having the formula Z is a radical selected from the class consisting of naphthyl, biphenylyl and phenoxyphenyl radicals, and m is a whole number equal to from 1 to 4.

In US. Patent 2,943,147 (and similarly in US. 2,391,450, issued December 25, 1945), issued June 28, 1960, and assigned to the same assignee as the present invention, there is disclosed and claimed a projection system employing a deformable medium having a high resistivity which is responsive to an electron beam which is velocity modulated. In general, this apparatus which is illustrated in FIGURE 1 of the attached drawing, comprises an evacuated glass envelope 10 containing an electron gun 11 for producing an electron beam 13 and deflecting it in a rectangular raster over the surface of a transparent, deformable medium 15 that is within a portion 17 of the transparent container; an enlarged view of this portion of the assembly is shown in FIGURE 2. The beam 13 is preferably velocity modulated by a television signal that is applied to the deflection means (not shown) in the electron gun 11. The deformable medium 15 has a center portion 19 of decreased thickness, coincident with the raster area of the beam 13, which is produced by electrons from the beam 13 that are attracted to a conducting coating 21 on the inner surface of the container 17. These electrons also produce deformations in the surface of the deformable medium 15, the amplitudes of which are a function of the number of electrons deposited by the beam 13 at the various points on the surface of the medium 15. Consequently, the amplitudes of these deformations are a function of the television signal modulating electron beam 13.

These deformations are utilized to diifract light from a light source 23 in an optical system which is illustrated as including a lens 24 that images light source 23 on the surface of medium 15 through a bar and slit system 25. Another lens 29 images the slits of system 25 on the bars of another bar and a slit system 31 in the absence of deformations in the surface of the deformable medium. However, any deformations phase diffract the light so that it passes through the slits in the system 31 with an intensity that corresponds to the amplitudes of the deformations and thus the amplitudes of the applied television signal. The light passing through system 29 is imaged by a projection lens 33 on a screen 35 after reflection from a mirror 37.

If a conventional deformable medium is utilized in the illustrated system, the average charge density produces a force on the medium 15 that overcomes the surface ten- 3,125,035 Patented Mar. 17, 1964 "ice sion from the excess medium outside the raster area and decreases the portion 19 of medium 15 to zero thickness; under such conditions no deformations can be formed and the system becomes inoperative until the medium is replaced.

In this U.S. Patent 2,943,147, it is stated that if the medium has the property of decreasing in resistivity with decreasing thickness, portion 19 does not decrease to zerothickness under the pressure of the charges but rather maintains a thickness the value of which is a function of the magnitude of charge density on the surface of the medium 15. With a decrease in resistivity, the time constant is decreased for the passage of leakage current from the surface of the deformable medium to the conducting coating 21 beneath it, resulting in increase in leakage current, which decreases the charge density on the surface of the medium, thereby relieving the pressure somewhat. Ultimately, an equilibrium condition is attained in which the pressure from the charges on the surface of the medium equals the pressure from the surface tension on the excess medium around the raster. Then the thickness at this equilibrium condition is maintained. The charge density on the surface of the medium never decreases to zero due to the leakage because it is continually being replaced by the eiectrons from the beam 13.

The deformable compositions described in the aforesaid U.S. Patent 2,943,147 as suitable for the medium are required to be transparent, be capable of withstanding electron bombardment without significant decomposition, have a viscosity at the operating temperature (between about 25 C. and 150 C.) of approximately to 50,000 centistokes, and the deformable composition must not decompose the conducting coating. The medium must also have a resistivity that varies within the range .of approximately 10 to 10 ohms-cm., with the average ,methylsilicone fluids containing up to 5% of phenyl sili cones, methyiphenyl silicones containing an average of two methyl and phenyl groups per silicon atom in which the mol ratio of methyl groups to silicon atoms is greater than 0 and less than 2, etc. However, it has been found that these deformable fluids are not as stable as one would desire because under the influence of an electron beam, the deformable medium or deformable fluid tends to increase in viscosity and with continued use of the projection system described above, the viscosity increases to a point where gel particles begin to form and ultimately the deformable medium gels; of course, this means that the apparatus can no longer be used with that particular deformable medium.

Unexpectedly, we have discovered that a group of organic compositions of Formula I described previously, is eminently suitable as the deformable medium in the above-described projection system Not only are sharp, viewable images of good light intensity obtained with these fluids, but also these fluids have exceptionally low vapor pressures and much greater resistance to irradiation and therefore are more stable in the presence of the electron beam used in the aforesaid projection system. The compositions employed by us in the aforesaid projection system can be used continuously for much longer periods of time without significant change in the deformable medium, thus adding greatly to the life of the projection system.

Within the scope of Formula I described above, many compositions can be employed for the purpose and the following examples are given by way of illustration and number of these compositions which can be employed as the deformable medium in the aforesaid projection sys tern. t is to be understood that where the biphenyl, naphthyl or phenoxyphenyl radical is present in the composition used as the deformable medium, the phenyl radicals of the biphenylyl group and the phenoxy radical of the phenoxyphenyl group may be ortho-, metaor parato the point of attachment in the biphenylyl or in the phenoxyphenyl radical shown in Formula I. Thus the biphenylyl radical may be illustrated as and the phenoxyphenyl radical may be illustrated as The naphthyl radical can be attached in the a or p positions.

EXAMPLE 1 This example illustrates the preparation of the compound tetra-(o-biphenylyl)silicate having the formula More particularly, 172 grams o-phenylphenol and 52 grams silicon tetrachloride were added to a reaction vessel and the mixture was heated for 3 minutes at a temperature of from 25 to 50 C. Thereafter 0.2 gram pyridine was added to the solution, and heating was continued at a temperature of 50l50 C. for an additional 12 minutes with rapid hydrochloric acid evolution. The mixture was heated thereafter for 7 minutes at a temperature of ISO-280 C. and for 4 minutes at a temperature of 280-310" C. The reaction mixture was then allowed to cool to 200 C. and 50 grams of additional o-phenylphenol was added, and the mixture was then heated for 7 minutes at 305 C. On fractional distillation of the reaction product, there was obtained a fluid boiling at 290300 C./ 19 which was identified as the aboveidentified composition of Formula II by the fact that it was found to contain 81.7% carbon and 5.2%% hydrogen, as contrasted to the theoretical values of 81.79% carbon and 5.15% hydrogen.

EXAMPLE 2 This example which illustrates the preparation of the compound bis-(m-phenoxyphenoxy)diphenylsilane having the formula III by filtration, and the reaction product washed with benzene. The solvent was then removed from the filtrate and the product was distilled under reduced pressure to yield a product which was then dried with anhydrous sodium bicarbonate and re-distilled to give the composition of Formula III boiling at 275277 C./ 0.15 mm. The identity of the compound was established by the fact that it was found to contain 78.3% carbon, 5.3% hydrogen, and to have a molecular weight of 561, as contrasted to the theoretical values of 78.23% carbon, 5.16% hydrogen and a molecular weight of 553.

EXAMPLE 3 This example illustrates the preparation of the composition having the formula IV CHaSi More particularly, employing the same conditions and procedure as in Example 2, 91.9 grams of o-phenylphenol and 39.2 grams pyridine in 200 ml. benzene were reacted with 23.4 grams of methyltrichlorosilane at elevated temperatures to yield a reaction product which upon fractional distillation gave the above-identified composition having Formula IV boiling at 255-258 C./ 0.01 mm. and having a n =1.63O1. Identification of this composition was established by the fact that it was found to contain 80.8% carbon, 5.7% hydrogen, and had a molecular weight of 530, as contrasted to the theoretical values of 80.69% carbon, 5.69% hydrogen, and a molecular weight of 551.

EXAMPLE 4 The composition having the formula CHuSi Q EXAMPLE 5 The compound tris-(m-phenoxyphenoxy)methylsilane having the formula was prepared by reacting similarly as was done in Example 2 a total of 97.3 grams m-phenoxyphenol and 39.2 grams pyridine in 200 ml. benzene with 22.4 grams methyltrichlorosilane. Distillation of the reaction product yielded the above-identified composition of Formula VI boiling at 275-277 C./0.05 mm. and having q =1.6042. Analysis established identity of the comwas prepared by reacting 100.5 grams rn-phenoxyphenol, 39.0 grams pyridine in 200 ml. benzene with 31.7 grams phenyltrichlorosilane. The phenyltrichlorosilane was added dropwise to the mixture of the other ingredients over a period of 2 hours and the mixture was then refluxed for an additional 1.5 hours. Pyridine hydrochloride was removed by filtration and the filtrate was washed -with benzene.

EXAMPLE 7 The composition bis-(o-phenylphenoxy)diphenylsilane having the formula was prepared by reacting diphenyldichlorosilane with o-phenylphenol in approximately equal molar ratios to give the aforesaid composition of Formula VIII, employing the same conditions as were used in the previous samples.

EXAMPLE 8 The composition o-biphenylyloxy-tris-(2-phenylethoxy)silane having the formula was prepared as follows. A total of 41.6 grams ethyl silicate and 34.0 grams o-phenylphenol was placed in a reaction vessel with 0.3 gram sodium methoxide as catalyst. The reaction vessel was then heated for 2.5 hours to a maximum temperature of about 165 C. during which time about 18 grams or ethanol were removed by distillation. The reaction mixture was then heated to 150 C. at .5 mm. to remove unreacted starting materials. After cooling, 733 grams 2-phenylethanol and an additional amount of 0.3 gram sodium methoxide were added, and an additional 17.1 grams of ethanol were distilled after heating to 160 C. Distillation of the reaction product under reduced pressure yielded a fiuid of the above Formula IX boiling at 260262 C./ 0.01 mm. and having a refactive index =1.5869.

6 The identity of the compound was established by the .fact that it contained 77.4% carbon, 6.5% hydrogen and had a molecular weight of 561, as contrasted to the theoretical values 77.11% carbon, 6.47% hydrogen and a molecular weight of 561.

EXAMPLE 9 The composition bis-(o-biphenyloxy)-bis-(2-phenylethoxy)si1ane having the formula X G s- 02 was prepared as follows. A total of 41.6 grams ethylsilicate and 68.1 grams o-phenylphenol were reacted in the same manner as was done with Example 8 using 0.3 gram sodium methoxide as catalyst, followed by reaction of 48.9 grams 2-phenylethanol and an additional 0.3 gram sodium methoxide. Distillation under reduced pressure yielded a fluid of the above Formula X boiling at 267-269" C./ 0.05 mm. Analysis of the compound showed it to contain 78.9% carbon, 5.9% hydrogen and had a molecular weight of 622, as contrasted to the theoretical values of 78.91% carbon, 5.96% hydrogen and a molecular weight of 609.

EXAMPLE 10 The composition tris(o biphenyloxy) phenylsilane having the formula was prepared similarly as was done in Example 6 with the exception that o-biphenylyl was used in place of the m-phenoxyphenyl of Example 6. Isolation of the above composition yielded a product which boiled at 290 C./ 0.015 mm.

In order to determine (by means of an accelerated test) the radiation resistance of the aforesaid compositions in an electron beam which would be the conditions under which these fluids would be expected to operate in the above-described projection system, the fluids of Examples 1-6 and 8-10 were subjected to electron irradiation with a 1500 kv. resonant transformer at a current input of 200-500 microamperes at a dose of 2050 10 roentgents/minute to a total dose of 400 rnegaoentgens. The following Table I shows the total number of molecules of gas per electron volts absorbed (identified as G gas), as well as the change in viscosity (in centistokes) prior to irradiation (identified as 1 cs.) and after irradiation (identified as 1 cs) at the temperature at which irradiation was measured.

Table I f Composition of Example G gas Temp. Vise. Temp. Vise.

saaaeae The low gas value and the small change in viscosity under the accelerated test conditions applied to the aboveidentiiied compositions as shown in Table I above established the eminent suitability of these compositions as the deformable medium in place of the deformable media disclosed in the aforesaid US Patent 2,943,147. When these compositions were placed in the projection system described in the attached drawing, clear images were obtained and the fluid could be used over long periods of time without any apparent evidence of either degradation or gelation of the deformable medium.

It will of course be apparent to those skilled in the art that in addition to the organosilane compositions described above as being useful for the claimed projection system, other organosilanes coming within the scope of Formula I can be employed without departing from the scope of the invention. Among such compositions which may be employed in addition to those recited above are, for instance, tris-(phenoxy)B-naphthylsilane having the formula XIII Si (O O H5) a tris- (,B-naphthyloxy methylsilane having the formula XIV CH3Si O a tris-(fi-naphthyloxy)B-naphthylsilane having the formula In addition to employing the above compositions alone, as the deformable medium, they can be mixed with other compositions, particularly organopolysiloxanes such as disclosed in Rochow patents US. 2,258,221 and 2,25 8,222, which can be used as the deformable medium. In one instance, an equal weight mixture of the composition described in Example 1 and a polydiphenylsiloxane of average molecular weight (determined ebullioscopically in benzene) between 1,000 and 1,500 was employed as the deformable medium in a projection system described previously. The conditions under which this test was carried out was a voltage of about kv., a current of 1.6 microamperes, and to use a temperature of about 130 C. for the deformable film. It was found that the life of this deformable mixture was well in excess of 1 hour when a static raster was employed, and there was no evidence of gelation even after the 1 hour period. In addition, the colors obtained by means of this deformable medium were exceptionally bright and clear, and the material had a very low noise level. The color contrast particularly in the red band was quite marked.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising a composition having the formula where R is a monovalent hydrocarbon radical selected from the class consisting of the methyl radical, aromatic radicals, and a radical having the formula Z is a radical selected from the class consisting of naphthyl, biphenylyl, and phenoxyphenyl radicals, and m is a whole number equal to from 1 to 4 inclusive, an electron beam means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting interior to subject the medium to a deforming force to produce deformations in the surface of said medium, and a light and optical system for projecting light as a function of the deformations in the surface of said medium.

2. A projection system comprising a container having a conducting interior, a deformable medium in said con tainer comprising a composition having the formula an electron means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting material to subject the medium to the deforming force ot produce the deformations on the surface of said medium, and a light and optical system for projecting light as a function of the deformations on the surfaces of said medium.

3. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising a composition having the formula CHaSi-O- an electron means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting material to subject the medium to the deforming force to produce the deformations on the surface of said medium, and a light and optical system for projecting light as a function of the deformations on the surfaces of said medium.

5. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising a composition having the formula I O I an electron means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating With said conducting material to subject the medium to the deforming force to produce the deformations on the surface of said medium, and a light and optical system for projecting light as a function of the deformations on the surfaces of said medium.

6. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising a composition having the formula an electron means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting material to subject the medium to the deforming force to produce the deformations on the surface of said medium, and a light and optical system for projecting light as a function of the deformations on the surfaces of said medium.

7. A projection system comprising a container having a conducting interior, a deformable medium in said container comprising a composition having the formula L Oi an electron means for producing an electrical charge on the surface of said deformable medium as a function of an applied electrical signal and cooperating with said conducting material to subject the medium to the deforming force to produce the deformations on the surface of said medium, and a light and optical system for projecting light as a function of the deformations on the surfaces of said medium.

No references cited. 

1. A PROJECTION SYSTEM COMPRISING A CONTAINER HAVING A CONDUCTING INTERIOR, A DEFORMABLE MEDIUM IN SAID CONTAINER COMPRISING A COMPOSITION HAVING THE FORMULA 